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Rare Disease Drug Pipeline and Clinical Trials

We understand that every scientific advancement counts when it comes to bringing new medicines to those in need. Of the 7,000 known rare diseases, less than 5% have an approved treatment option.1 This gap in care has spurred a sense of urgency—to find new, potentially life-changing approaches today.


Pfizer Rare Disease merges pioneering science with a deep understanding of the underlying disease pathology to deliver innovative treatments. With over three decades of experience in rare disease, our broad global rare disease portfolio aims to address the unmet medical needs across a number of therapeutic areas, including hematology, neurology, endocrinology, cardiology, and inherited metabolic diseases.

  • Gene Therapy

    Four out of five rare diseases are genetic1, so Pfizer is exploring a new potentially transformative approach to treat genetic disease through gene therapy. We are well positioned to lead advances in gene therapy research through our scientific expertise, global reach, and more than three decades of experience in rare diseases.

    Our approach to gene therapy works by delivering a functioning gene to a targeted tissue in the body, potentially enabling the tissue to produce a protein that is either missing or nonfunctioning in patients with some genetic diseases.

    Pfizer Rare Disease is focused on developing recombinant adeno-associated virus (rAAV) precision-targeting gene therapies, because of its potential to consistently target cells with treatment. This technology can be standardized and customized, and has the potential to streamline the manufacturing and regulatory path toward more efficient drug approval.

    Currently, we are prioritizing single gene defect diseases, such as Duchenne muscular dystrophy (DMD), hemophilia, and amyotrophic lateral sclerosis (ALS), and we have a robust pipeline of potential gene therapy treatments in preclinical and clinical development. In the future, we hope to apply our gene therapy technology to the treatment of more common, complex diseases, where multiple genes are involved, such as central nervous system diseases and heart disease.

    We are here to learn and drive innovation through active collaboration and partnership:

    • With the acquisition of Bamboo Therapeutics in 2016, we expanded our portfolio to advance recombinant AAV-based gene therapy technology and have our first candidate in the clinical development stage. Our Phase 1b clinical trial for PF-06939926, a gene therapy candidate for DMD, is underway, and our Phase 3 clinical trial will be initiated in 2021.
    • Following the transfer of the responsibility of the program from Spark Therapeutics to Pfizer, we initiated our pivotal Phase 3 program, which is evaluating the investigational gene therapy fidanacogene elaparvovec for the treatment of hemophilia B.
    • We also have an exclusive, global collaboration and license agreement with Sangamo Therapeutics, Inc. for the development and commercialization of gene therapy programs, which currently includes an ongoing Phase 1/2 trial in hemophilia A, and a preclinical program in amyotrophic lateral sclerosis (ALS). Following the transfer of the IND for giroctocogene fitelparvovec (formerly SB-525, now PF-07055480), we initiated our Phase 3 trial evaluating giroctocogene fitelparvovec gene therapy for the treatment of severe hemophilia A.

    The future is here. By digging deeper, asking bold questions, and leading scientific innovation, Pfizer Rare Disease is striving to go beyond disease control toward developing potentially transformative medicines and supporting healthy living at all stages of life.

    Learn more about our work in gene therapy.

  • Hemophilia

    Prior to the 1960s, average life expectancy of a male with hemophilia, a blood-clotting disease that causes abnormal bleeding, was 12 years of age2. Today, it is a treatable rare disease, and patients who receive treatment can expect to live longer, healthier, more active lives3. Pfizer Rare Disease is grounded in our heritage in and commitment to the hemophilia community. For almost three decades, we’ve helped support the hemophilia community through tailored resources and programs to amplify the patient voice, champion their successes, and support them through some of their greatest challenges. While approved treatment options make hemophilia a manageable condition, we believe that more can be done to advance the science that will help achieve the breakthroughs of tomorrow.

  • Transthyretin Amyloidosis

    Transthyretin amyloidosis (ATTR Amyloidosis) is a rare, progressive disease characterized by the buildup of abnormal deposits of amyloid proteins composed of misfolded transthyretin protein in the body’s organs and tissues4,5.

    This disease can impact numerous areas of the body, and the damage caused by the buildup of the amyloid deposits is debilitating and irreversible, and is universally fatal4,5. There are two presentations of ATTR amyloidosis, which include ATTR-PN and ATTR-CM6. A lack of awareness and understanding of ATTR amyloidosis has led to low diagnosis rates, and there are limited treatment options available to those who eventually are diagnosed7,8,9.

    Pfizer Rare Disease is at the forefront of advancing the care of people with ATTR amyloidosis, and improving disease awareness and understanding. Our research is helping to better understand the early signs and symptoms, disease epidemiology and progression, and burden of illness for both patients and caregivers.

    Currently, Pfizer is focused on two specific presentations of the disease:

    • Transthyretin Amyloid Cardiomyopathy (ATTR-CM): In ATTR-CM, buildup of amyloid primarily occurs in the heart, and leads to restrictive cardiomyopathy and progressive heart failure10. This presentation of the disease can be inherited or can be associated with aging5,11.
    • Transthyretin Amyloid Polyneuropathy (ATTR-PN): ATTR-PN results from a genetic mutation of the transthyretin gene, when amyloid fibrils form in the peripheral and autonomic nerves12,13.

    As part of our commitment, Pfizer Rare Disease is conducting ongoing research in ATTR amyloidosis and supports the Transthyretin Amyloidosis Outcomes Survey (THAOS), the largest, ongoing, real-world international database for ATTR amyloidosis. THAOS collects data from patients with ATTR amyloidosis, including both inherited and wild-type disease, and asymptomatic patients with TTR mutations, in order to improve disease knowledge, understanding, and management of people with this disease.

  • Duchenne Muscular Dystrophy

    Duchenne muscular dystrophy (DMD) is a rare, serious, debilitating childhood genetic disease characterized by progressive muscle degeneration that leads to injury and weakness, and a significantly shortened life expectancy. DMD is the most common form of muscular dystrophy worldwide and primarily affects boys14. There is an urgent need to advance DMD research because there are limited treatment options available15.

    DMD is a focus area of clinical research for Pfizer Rare Disease and we are currently investigating gene therapy as a potential option to address the underlying cause of the disease.

Work with Us

If you’re interested in collaborating with our Rare Disease research team and want to learn more about our work, visit our Rare Diseases Partnering page. We welcome the opportunity to discuss how we can work together. 


1. Global Genes. Rare Facts. Accessed February 10, 2020.

2. National Organization for Rare Disorders. Hemophilia B. Accessed February 10, 2020.

3. Franchini M, Mannucci P. Past, Present and Future of Hemophilia: A Narrative Review. Orphanet J Rare Dis. 2012;(7):24.

4. Ruberg FL, Berk JL. Transthyretin (TTR) cardiac amyloidosis. Circulation. 2012;126(10):1286-1300.

5. Ando Y, Coelho T, Berk JL, et al. Guideline of transthyretin-related hereditary amyloidosis for clinicians. Orphanet J of Rare Dis. 2013;(8):31.

6. Stewart M, Alvir J, Cicchetti M, et al. Characterizing the High Disease Burden of Transthyretin Amyloidosis for Patients and Caregivers. Neurol Ther. 2018;7(2):349-364.

7. Rapezzi C, Lorenzini M, Longhi S, et al. Cardiac amyloidosis: the great pretender. Heart Fail Rev. 2015;20(2):117-124.

8. Shirota Y, Iwata A, Ishiura H, et al. A case of atypical amyloid polyneuropathy with predominant upper-limb involvement with diagnosis unexpectedly found at lung operation. Intern Med. 2010;(49):1627-1631.

9. Pareyson D. Diagnosis of hereditary neuropathies in adult patients. Neurology. 2003;(250):148-160

10. Siddiqi OK, Ruberg FL. Cardiac amyloidosis: an update on pathophysiology, diagnosis and treatment. Trends Cardiovasc Med. 2017;1050-1738.

11. Swiecicki PL, Zhen DB, Mauermann ML, et al. Hereditary ATTR amyloidosis: a single-institution experience with 266 patients. Amyloid. 2015;22(2):123-131.

12. Benson MD, Kincaid JC. The molecular biology and clinical features of amyloid neuropathy. Muscle Nerve. 2007;(36):411-423.

13. Hou X, Aguilar M-I, Small DH. Transthyretin and familial amyloidotic polyneuropathy: recent progress in understanding the molecular mechanism of neurodegeneration. FEBS J. 2007;(274):1637-1650.

14. NIH National Human Genome Research Institute. About Duchenne Muscular Dystrophy. Accessed February 10, 2020.

15. National Organization for Rare Disorders. Duchenne Muscular Dystrophy. Accessed February 10, 2020.